Some commercially available audio appliances, including headphones and earphones, incorporate one or more microphone transducers suitable for converting incident acoustic energy (e.g., contained in sound waves) to one or more corresponding electrical signals. Depending on an environment in which such an audio appliance is used, the incident acoustic energy may include an impairment (or distractor) to a desired audio signal. For example, in a café setting, observations of a user's speech (e.g., the desired signal) can be impaired by clattering dishes, ambient music, others' speech, etc. Such impairments can range from being barely perceptible in an observed signal to rendering a desired audio signal unintelligible in the observed signal.